Cooling system

Abstract

A cooling system has a configuration in which a cooling system for an inverter device and a motor generator also serves as a cooling system for a battery. In this configuration, a control device performs temperature-raising control of the battery when a battery temperature is below a prescribed temperature lower limit value. The control device controls an operation of a switching valve such that cooling water from a cooling medium path is outputted to a bypass path. Further, if a cooling water temperature is lower than a prescribed temperature, the control device controls the inverter device such that a power loss during a switching operation in a switching element included in the inverter device becomes larger than a power loss during normal control. As a result, the cooling system having a small-sized, low-cost configuration rapidly recovers capacity decline of the battery, which occurs at low temperatures.

The invention claimed is: 
     
       1. A cooling system, comprising:
 a load drive device having a power storage mechanism configured to be chargeable/dischargeable, and a drive circuit receiving supply of electric power from said power storage mechanism and driving an electric load; 
 a cooling device cooling said load drive device; and 
 a control device controlling an operation of said load drive device and an operation of said cooling device, 
 said cooling device including a cooling medium path allowing a cooling medium to pass therethrough, 
 said power storage mechanism being disposed to share said cooling medium path with said drive circuit, 
 said control device including a temperature-raising control unit performing temperature-raising control of said power storage mechanism when a temperature of said power storage mechanism is below a prescribed temperature lower limit value, and 
 said temperature-raising control unit including
 an estimation unit estimating an amount of heat generated from said drive circuit, and 
 a drive control unit controlling said drive circuit such that a power loss generated at said drive circuit becomes larger than a power loss during normal control, when the amount of heat generated from said drive circuit, estimated by said estimation unit, falls short of an amount of heat required for warming said power storage mechanism. 
 
 
     
     
       2. The cooling system according to  claim 1 , wherein said cooling device includes
 a radiator disposed at said cooling medium path and cooling said cooling medium, 
 a bypass path for bypassing said radiator, and 
 a switching valve allowing said cooling medium to pass through any of said radiator and said bypass path, and 
 said temperature-raising control unit further includes a switching valve control unit controlling an operation of said switching valve such that said cooling medium passes through said bypass path. 
 
     
     
       3. The cooling system according to  claim 2 , wherein
 said drive circuit includes an electric power converter which performs electric power conversion between said power storage mechanism and said electric load by a switching operation of a switching element, and 
 said drive control unit controls said drive circuit such that a power loss generated during said switching operation becomes larger than the power loss during the normal control. 
 
     
     
       4. The cooling system according to  claim 3 , wherein said drive control unit controls a drive power supply of said switching element such that conduction resistance in a state where said switching element is turned on becomes higher than conduction resistance during the normal control. 
     
     
       5. The cooling system according to  claim 3 , wherein said drive control unit controls a drive power supply of said switching element such that conduction resistance in a state where said switching element is turned off becomes lower than conduction resistance during a normal operation. 
     
     
       6. The cooling system according to  claim 3 , wherein said drive control unit controls said drive circuit such that a switching speed of said switching element becomes lower than a switching speed during a normal operation. 
     
     
       7. The cooling system according to  claim 6 , wherein said drive control unit switches an electrical resistor electrically connected between a drive power supply of said switching element and a control electrode of said switching element, from a first resistance value to a second resistance value larger than said first resistance value. 
     
     
       8. The cooling system according to  claim 3 , wherein
 said electric load is a rotating electrical machine, and 
 said drive control unit controls said drive circuit such that driving efficiency of said rotating electrical machine becomes lower than driving efficiency during a normal operation. 
 
     
     
       9. The cooling system according to  claim 8 , wherein
 said rotating electrical machine operates at a first operating point which requires a drive current having a first current amplitude for generating requested torque, during the normal operation, and 
 said drive control unit controls said drive circuit such that said rotating electrical machine operates at a second operating point which requires a drive current having a second current amplitude for generating said same requested torque, said second current amplitude being larger than said first current amplitude. 
 
     
     
       10. The cooling system according to  claim 1 , wherein said estimation unit estimates the amount of heat generated from said drive circuit, based on any of a temperature of said cooling medium, a temperature of said drive circuit, and a drive current flowing through said drive circuit. 
     
     
       11. The cooling system according to  claim 10 , wherein said power storage mechanism is disposed to share said cooling medium path further with said electric load.